This invention relates to material handling apparatus, and more particularly to a closed system for handling powdered or fine granular, fluent materials, the system enabling the fluent material to be readily loaded into and unloaded from a container substantially without the discharge or escape of dust.
In handling many powdered or granular fluent materials, such as paint pigments, cement, diatamoceous earth and the like, and especially in handling toxic powdered materials, it has long been a problem to effect rapid and controlled loading of the material into its container and the rapid unloading of the material without dispensing substantial quantities of dust into the atmosphere. For example, in filling paper bags, drums, or other containers with a powder, substantial quantities of dust are often generated. While this dust can oftentimes be collected or otherwise controlled at the factory in which the bags are filled, the end use of the bags may result in the excessive release of dust which cannot readily be controlled. This release of dust, especially the release of toxic dust, not only creates a housekeeping problem in the area of use, but the toxic dust may constitute a health hazard to many workers and other personnel in the general vicinity.
As disclosed in U.S. Pat. Nos. 3,777,775 and 4,007,694 and in my U.S. patent application Ser. No. 801,865, filed May 31, 1977, issued as U.S. Pat. No. 4,149,755, Apr. 17, 1979, containers are now commercially available from Semi-Bulk Systems, Inc. of St. Louis, Mo., under their registered trademark "Air Pallet" for receiving, transporting and unloading "semi-bulk" quantities (e.g., 2000-4000 pounds or more) of powdered or finely divided granular material. Generally, such containers have a rigid molded plastic pallet base and a flexible plastic film bag secured thereto. The bag is open at its mouth, and, as shown in U.S. Pat. No. 4,054,161, equipment is presently available for filling the open mouth bags of such containers with powdered material while minimizing the dust generated during filling. Specifically, this prior filling apparatus has a collapsible unbrellatype closure which is selectively expanded to hold the mouth of the bag open, to seal the mouth of the bag while the product is being delivered into the bag via a vertical fill tube and to support the bag during filling. Upon completion of filling of the bag, the umbrella seal is collapsed and raised, and workmen then manually gather the sides of the bag to the center, twist the open mouth shut, and secure it with a twisted wire tie. However, upon gathering of the open bag a certain amount of dust from within the container is oftentimes expelled. Workmen may thus be exposed to the dust while they are manually gathering and tying the bag closed. However, when handling toxic materials, it may be unacceptable to expose workmen to even small quantities of dust.
It is inherent that a small quantity (for example, a few pounds) of the powdered material will remain in the container after it has once been filled and unloaded. As described above, the bags of prior containers must be fully opened prior to refilling in the filling apparatus. This exposes workmen to the residual dust within the container. Still further, the bags of the prior containers must be periodically replaced. This also may expose workmen refurbishing the containers to toxic dust remaining within used containers.
Reference may also be made to such U.S. Pat. Nos. as Re. 23,504, 2,531,743, 2,815,621 and 2,954,204 which disclose various apparatus for filling containers with powders in the same general field as the present invention.